At the junction of a semiconductor and a metal, the initial mismatch in chemical potentials of the two materials leads to an electric field in the semiconductor as charge crosses the interface to equalize these potentials. The resulting electric field or depletion width affects the photoluminescence behavior in the semiconductor since electron-hole pairs that are generated in this zone are separated by the field and thus cannot radiatively recombine. We propose to explore this phenomenon as a probe of electronic structure of titanium-nickel thin film. TiNi shape- memory alloy undergoes a solid-state phase change which is expected to alter the Fermi levels in the underlying semiconductor. There is a possibility of developing a transducer which is sensitive to the crystalline state of TiNi and may be a sensitive miniature chemical probe. We will prepare films of TiNi shape-memory alloy in thicknesses varying from a few thousand angstroms to several microns, sputtered onto a variety of substrates. These test samples will be studied by photoluminescence as the temperature is varied through the transition temperature of the TiNi film. The expected result is a significant shift in the spectrum and/or intensity of emitted light when the phase change occurs.
